Question: What is headshaking and what can you do about it?
Answer: Headshaking has a multitude of different causes. It is often difficult to establish the exact cause in each case, even when extensive diagnostic tools are employed. This makes it notoriously challenging to treat, and several different treatment modalities have been put forwards to help to control the condition.
One of the more common causes of headshaking is an over-reactive trigeminal nerve. The trigeminal nerve is a nerve that allows the face to detect sensations – humans also have a trigeminal nerve for exactly the same purpose. The nerve is stimulated by light, touch and cold air on the nose or nostrils, facial skin and teeth. In headshakers with an oversensitive trigeminal nerve as the cause, the horse reacts to a sensation that a ‘normal’ horse would not really notice.
Some owners, in trying to treat the condition have therefore used nose nets and sun visors to try and reduce the amount of stimulation the trigeminal nerve experiences. These solutions can work for some horses, and may be worth trying especially as a first step as they are both reasonably cheap and non-invasive options.
PENS (Percutaneous Electrical Nerve Stimulation) is another treatment option, and this therapy works by acting as a neuromodulator. Essentially the therapy involves the application of electrical stimulation to the trigeminal nerve and its branches, whilst the horse is sedated. This stimulation of the nerve is thought to decrease its sensitivity, eventually making the nerve less reactive.
Magnesium supplements and salt in the diet are thought to also be of benefit, as they are believed to have neuroprotective effects on nerve firing, and are thus thought to reduce the pain generated by oversensitive nerves.
Finally, some horses only really shake their heads during certain seasons, like spring and summer. In these cases, as allergies are likely to be related, antihistamines can help, as they have been shown to reduce sensitivity in some horses to both light and pollen. If a a seasonal component to the headshaking is suspected, a vet should be contacted for further advice.